This application is based on and incorporates herein by reference Japanese Patent Applications No. 2000-56579 filed Mar. 2, 2000 and 2000-78433 filed Mar. 21, 2000.
1. Field of the Invention
This invention relates to an apparatus for vehicles for detecting forward condition such as information existing ahead of a vehicle and related to safety drive.
2. Related Art
Laser radar devices are proposed to detect vehicle forward condition such as road conditions, preceding vehicles and the like. The laser radar device is generally installed on a front bumper of a vehicle. The laser radar device radiates a laser beam forward in a predetermined angle relative to the reference plane such as the ground plane as long as the vehicle posture is stable, for instance, when the vehicle is at rest or in a cruising condition. As a result, the laser radar device is enabled to receive a reflected beam from a front object and detect the front object as the forward condition based on the received beam.
The laser beam is radiated in the more upward direction than in the predetermined angle direction, when the vehicle is loaded with heavy stuff at the rear side or the vehicle is accelerated. The laser beam is radiated in the more downward direction than in the predetermined angle direction, when the vehicle is decelerated. In those instances, the forward condition detecting operation will be affected by the vehicle posture.
It is therefore an object of the present invention to provide a forward condition detecting apparatus which is capable of detecting forward condition without being affected by changes in vehicle drive condition or loading.
It is another object of the present invention to provide a forward condition detecting apparatus which is simple in construction and is capable of being driven together with a front headlight lamp.
A forward condition detecting apparatus for vehicles has a laser radar device which detects forward condition of a vehicle. An electronic control unit calculates an angle of inclination of the vehicle. The electronic control unit then calculates a radiation angle based on the calculated angle of inclination. The electronic control controls an angular position of the laser radar device based on the calculated radiation angle so that a laser beam may be maintained radiated generally in parallel with the reference plane irrespective of the inclination of the vehicle. The angle of inclination of the vehicle is calculated based on a difference between a front height and a rear height of the vehicle.
Preferably, the laser radar device is provided in a front headlight unit and driven together with a front headlight lamp in response to the calculated angle of inclination.